title: Semifield assessment of the runoff potential and environmental risk of the parasiticide drug ivermectin under Mediterranean conditions.
abstract: BACKGROUND
  The antiparasitic ivermectin is of particular concern to regulatory agencies. Ivermectin can reach the environment through the direct emission of dung from livestock on pasture and via manure application on agricultural lands.
  
  
  METHODS
  A semifield study was conducted for assessing the ivermectin dynamic in runoff and drainage waters from dung-treated soils placed on experimental trays. The experiment was conducted under natural Mediterranean conditions. Realistic pasture and arable land applications were assessed using dung of treated animals and compared with a positive control (spraying the ivermective solution without dung).
  
  
  RESULTS
  Similar concentrations were obtained in all three treatments for drainage waters, with values ranging from <5-10 to about 20 ng/l. However, strong treatment-related variation was observed in runoff waters, with the highest concentrations found in the spray treatment (9-188 ng/l), followed by the arable land (<5-88 ng/l) scenario, and concentrations not exceeding 6 ng/l in the pasture scenario. Ivermectin levels in runoff particles were up to 1,660 and 5,890 ng/kg dry weight for the pasture (I1) and arable land (I2) scenarios, respectively. Ivermectin was only detected in the drainage and runoff waters collected in the first rainfall events after treatment.
  
  
  CONCLUSIONS
  The measured concentrations in water (0.006-0.118 ng/ml) and runoff particles (0.052-5.89 ng/mg dry suspended matter) are orders of magnitude higher than those provoking effects on aquatic and benthonic communities under experimental and mesocosm conditions, suggesting a clear risk for aquatic systems in the vicinity of pasture areas of treated animals or arable soil fertilized with its manure.
authors.affiliation: Laboratory for Ecotoxicology, Department of the Environment, Spanish National Institute for Agricultural and Food Research and Technology, Carretera A Coruña Km 7.5, Madrid, Spain. torija@inia.es
authors.forename: Carlos
authors.initials: C
authors.lastname: Fernández
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Porcel
authors.forename: Alvaro
authors.initials: A
authors.lastname: Alonso
authors.forename: Manuel
authors.initials: M
authors.lastname: San Andrés
authors.forename: José Vicente
authors.initials: JV
authors.lastname: Tarazona
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D000977:Antiparasitic Agents / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D004784:Environmental Monitoring; D007559:Ivermectin / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D058751:Livestock; D019083:Mediterranean Region; D018570:Risk Assessment / Q000379:methods; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D014730:Veterinary Medicine; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity
chemical_list: D000977:Antiparasitic Agents; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; D007559:Ivermectin